Green’s Dictionary of Slang

see twenty-four carat adj.

1. (US black) $2; $20.

1959		Esquire Nov. 70I: This gig pays twenty cents a night.
1961		R. Russell Sound 157: Twenty cents meant twenty dollars; Red always spoke of dollars in amounts under one hundred as cents; perhaps it expressed his contempt for money.

2. (N.Z. prison, also twenty-five center) a gullible person, considered ‘not all there’.

2001

D. Looser Boobslang [U. Canterbury D.Phil. thesis] 195/1: twenty cents n. an idiot, a naive gullible person who is easily conned [...] twenty-five-center n. a considered an idiot.

(US) $20 worth of drugs, usu. marijuana or crack cocaine.

1994		Dogg Pound ‘What Would U Do’ 🎵 Yeahhh, back up in yo ass with a twenty sack. / Don’t wanna fuck with me.
1995		2Pac ‘Young Niggaz’ 🎵 Hit the freeway, let the wind blow, drop the window / Workin with a twenty sack of indo, feelin good.
1999		transcript of State v. Middlebrooks (Court of Appeals for Montgomery County (OH), No. 15671) 🌐 At trial, Lee testified that Micah told the defendant that he wanted a twenty sack ($20 worth of marijuana), so the defendant began to prepare the marijuana [etc.].
2001		O.G. Spanish Fly ‘Hotel Motel’ 🎵 I said I’m kicking back with a twenty pack / And I’m smoking doser from a twenty sack.

(US Und.) a con-man who is unable to keep the victim from complaining after he has lost his money.

1909

W. Irwin Confessions of a Con Man 124: And he wasn’t one of those ‘twenty-minute men’ who can’t hold a sucker after the touch.

a money lender.

1952

J. Jones From Here to Eternity (1998) 34: If you don’t get me that rating so I can get some of it, I’ll be in debt to the twenty percent man.